Chemo-stratigraphical Characterization in the Upper Eocene, Southeastern Gulf of Mexico: Insights from XRF-XRD Integration

Summary The study area is located at Block #26 within the Salinas Basin, specifically in Deep Water at the southeastern Gulf of Mexico, where geological complexities in the Upper Eocene formations were observed. In this stage, the region has a distinctive geological history, marked by the interaction between the Caribbean and the southern Gulf of Mexico. The main challenges faced in the region were caused by sediment provenance, diagenesis, authigenic mineral formation, and hydrothermal alteration. The methodology used a multi-faceted approach, integrating elemental ratios from XRF analysis, mineralogical identification through XRD, and chemostratigraphical evaluation. Our study emphasises a robust Quality Control framework during sample acquisition to prevent mixing and ensure accurate depth allocation. Our research monitored the potential contribution of radioactive minerals in non-shaly rocks, particularly in high Th, U, and K₂O values, a critical limitation associated with downhole GR logs. The results reveal a distinctive signature in the elemental ratios, with an increase in MgO, Cr, Ni, and Co, coupled with a depletion in K₂O, Al₂O₃, and CaO. Mineralogical shifts identified through XRD have confirmed a marked decrease in the Total Clays and Total Carbonates, along with a rise in Quartz, Feldspars Minerals, and the occurrence of Enstatite and Chrysotile.